Refugee Bushra, 19, who fled her home in Syria 17 days ago, holds her son Omar, 2, as she registers at the UNHCR center in the northern city of Tripoli, Lebanon, Wednesday. She was declared the millionth refugee to leave the country.

By Ian Johnston, Staff Writer, NBC News

The number of refugees fleeing Syria has hit a million — nearly 5 percent of the population — the United Nations said Wednesday, as the U.K. announced it planned to send armored vehicles to the rebels fighting President Bashar Assad’s regime.

They arrived in neighboring countries "traumatized, without possessions and having lost members of their families," it added.

"With a million people in flight, millions more displaced internally, and thousands of people continuing to cross the border every day, Syria is spiralling towards full-scale disaster," U.N. High Commissioner for Refugees António Guterres said.

"We are doing everything we can to help, but the international humanitarian response capacity is dangerously stretched. This tragedy has to be stopped,” he added.

Guterres said the impact of such large numbers of people arriving in Syria’s neighbors was severe.

The statement said that Lebanon's population had increased by "as much as 10 per cent," while Jordan's energy, water, health and education services "are being strained to the limit."

Last week, Secretary of State John Kerry signaled a change in U.S. policy, saying military rations and medical supplies would be sent directly to Syrian opposition fighters. He also said the U.S. would provide $60 million in new aid to help opposition groups provide basic goods and services.

Scud missiles used on civiliansSpeaking in the U.K. parliament Wednesday, British Foreign Secretary William Hague said the conflict in Syria had reached "catastrophic proportions," with 70,000 people estimated to have died.

He said that the U.K. would provide equipment to protect civilians, including armored four-wheel drive vehicles "to help opposition figures move around more freely," and body armor.

"The regime has used 'scud' ballistic missiles against civilian areas. And the U.N. Commission of Inquiry for Syria has found evidence of grave human rights violations, war crimes and crimes against humanity; including massacres, torture, summary executions and a systematic policy of rape and sexual violence by the regime’s forces and its militia," he said.

He said diplomacy was "taking far too long and the prospect of an immediate breakthrough is slim."

"The international community cannot stand still in the face of this reality," Hague added.

Bushra, a 19-year-old mother of two, was declared the symbolic millionth refugee by the UNHCR after she was registered in Tripoli, Lebanon, Wednesday.

"Her flight to Lebanon was a desperate last measure. She moved with her children from the city of Homs, where she lived, and sought safety in several villages to avoid tanks and shelling and gangs of men whom she feared would rape or kill her and her little ones," the UNHCR statement said.

"But soon, she said, the shooting would begin, the shelling would rain down and it would be time to leave," it added. Her husband, a truck driver, is missing.

"We need help," Bushra said, according to the statement. "We hope this will end so we can go back to our house. We need to feel peace and stability. We cannot ask for anything more."

In Beirut, Panos Moumtzis, the UNHCR regional coordinator for Syrian refugees, told The Associated Press that 7,000 Syrians have been crossing into neighboring countries every day since the fighting escalated in December.

"When you stand at the border crossing, you see this human river flowing in, day and night," Moumtzis said after inspecting UNHCR's registration centers at border crossings in Lebanon.

He told the AP that the U.N. refugee agency badly needed money to help host countries cope and manage the refugee population.

He added the agency was only able to provide Syrians fleeing violence with a bare minimum: a tent, a blanket, a sleeping mat, 2,000 calories a day and 20 liters of water a day.